When Pike relinquished command of the Enterprise to James Kirk, Number One was assigned a command of her own. (TOS novel Enterprise: The First Adventure)

In the 24th century, a human immortal called Morgan Primus may be the same person as Number One.

In the New Frontier novels, Peter David plays with Primus's physical resemblance to Lwaxana Troi, Christine Chapel, Number One, and even the computer's voice—all characters played by Majel Barrett. He has since stated that Primus is not the same person as Chapel.

Number One was said to be from Betazed, and telepathic, in this continuity.

In 2264, Number One received transfer orders to serve as science officer on the Potemkin. While thwarting the plans of the vampiric alien Akia to take over Enterprise, however, she was killed aboard the shuttlecraft Agamemnon. (Orion Press: Drink Deeply)

Number One was offered command of the USS Lexington in 2261, which she turned down. Three years later, she also turned down command of the USS Antares. When Pike is promoted to fleet captain, she was offered -- and accepted -- command of the Yorktown.

When the incident that cripples Pike occurs in 2266, she and Yorktown are on patrol in the Neutral Zone, but received a communiqué from Commodore Mendez. While Number One traveled to Starbase 11 as quickly as possible, Pike had left orders that no one -- not her, not Philip Boyce, not Robert nor Sarah April -- would be allowed to see him.

Over the next few years, Number One and Dr. Boyce got together once a year to talk about Pike and reminisce. It is not until 2270, after the end of Kirk'sfive-year mission, that Spock tells them what the Talosians did for Pike. (Paradigm Shift: "No Small Dreams")

It was revealed during the Talos IV mission that she also harbored an attraction for Pike. She eventually married José Tyler. If she is indeed Morgan Primus, she has a single daughter, Robin Lefler. (Star Trek: New Frontier novels)